Mount & Blade.
http://www.taleworlds.com/Free download. Lets you get up to level 6 with the demo.
I don't have that limitation (I bought it!) Use the page I gave you for screenshots.

This is the most fun I've had playing a game. Riding a horse, shooting arrows at the enemy, fighting in a huge battle of 40 men (okay, 40 men isn't huge...), swinging a sword and wielding a shield and choosing when to block...
It's WAR! Fun fun fun war. No magic spells, no hiding in the shadows and killing someone from behind without them knowing you're there...

If you like medieval games, you'd probably love this. A kinda steep learning curve to get GOOD at it, but it's basically pick it up and play it. Money doesn't grow on trees, and things are literally priced. The GOOD armor (plate) costs an arm and a leg, and only the truely rich could afford it, like in medieval times.

Did I mention the modding capabilities? Like, the Lord of the Rings mod that lets you play on one of 4 sides?